Electric heater.



C. P. MADSEN.

ELECTRIC HEATER.

APPLIGATION FILED JULY 9, 1910.

1,007, 1 25, Patented 0ct.31, 1911.

. l 3 SHEETS-SHEET 1.

C. P. MADSEN.

ELECTRIC HEATER.

APPLICATION FILED JULY9,1910.

1,007,125, Patented 0013.31,19-11.

3 SHEETS-SHEET 3.

fwerzlor Char/@s Madsen To all whom'it may concern:

' Unrrnn STATES Parana* OFFICE.

CHARLES I. MADSEN, OF CHICAGO, ILLINOIS, ASSIGNOR TO PELOUZE ELECTRIC HEATER CO., OF CHICAGO, ILLINOIS, A. CORPORATION OF ILLINOIS.

ELECTRIC HEATER.

i' Specification of Letters Patent.

Patented oct. 31, 1911.

Application filed .Tuly 9, 1910. Serial No. 571,235.

Be it known that I, CHARLES P. MADSEN, a citizen of the United States, and resident of Chicago, Cook county, Illinois, have invented certain new and useful Improvements in Electric Heaters, of which the following is a full, true, clear, and exact description, such as will enableothers skilled` in the art to which it appertains to make and use the same. A I.

My invention relates to that class of electrically heated devices known" as bread toasters, meat broilers, air warmers and the like.

The object of my invention is to provide an electric heating device of this character in whichthe heat generated by the heating element will -be imparted or Itransmitted to the object or material to be heated radiantly` through the atmosphere surrounding and containin the heating element, and in which the heat imparted will be confined upon an area where it will be most effective and will not become dissipated in other parts of the device, thereby increasing the eective heating capacity and the heating speed ofthe heater for a given current consumption.

A further object of my invention contem'` plates the provision of an electric heater having a heating element or heat generator which will be independent of its containing case or receptacle and removable therefrom as a unit, and which will be comparatively inexpensive to manufacture whereby the heating element may be conveniently removed and renewed at slight cost by the user of the device, should it become damaged or injured in any manner.

Further and more particular objects of my invention are to provide a heater which will be compact and neat in appearance; which will be portable and which will have means for quickly and eii'ectively making and breaking electrical connection with the heating element; and which will be particularly adapted for toasting bread and for broiling or frying meats `and other food products. y

I will explain my invention further by reference to' the accompanying drawings in which: Figure 1 is a' top plan view of an electric heater structure embodying my in vention; Fig. 2 is a longitudinal sectional view on line-2 2 of Fig. 1; Fig. 3 is a view in side elevation showing an lnvertible pan 0r tray used in lconjunction with my electric heater for rendering it adaptable for frying meats, griddle cakes and other food' products; Fig. 4 is a view in end elevation showing the plug socket and the terminals `for the heating element; Fig. 5 is a view in section on line 5 5 of Fig. 1; Fig. 6 is a top plan. view of the unit heating element retacle; 7 is a view of the under side of said heating element showing the connecting plug in relative position; Fig. 8 is an enlarged, transverse, sectional view showing the relation of the food grid, the heating element and the heat reflector; Figs. 9 and 10 are enlarged -detail sectional viewsshowing the means of securing the food-grid and the unit heating element in position; and Figs. 11, 12, 13 and 14 aredetail views of the connection plug for connecting the heater to an electric circuit.

I have discovered by extensive experiment that, in a certa-in class of heaters, it theheating element is maintained out of mechanical. contactI with the object or material to be heated and with any other object and instead is arranged so that it imparts its generated heat to the object or material to be heated by radiation through the medium of the atmosphere surrounding the heating element, the eliiciency and effective heating capacity of the heating element lwill be greatly increased for a given'current consumption. The difficulties which are presented in a heating devcie of this sort lie in arranging the heat-ing element so that it will impart or transmit alll of its generated heat to the external object, and preventing the loss or dissipation of heat at points Where it will not be effective in heating the external object or material. I have discovered that the highest eiciency, the most effective heating capacity and the maximum heating speed can be attained by disposing the external, object to be heated at a given distance from a heatingelement of a given temperature. I have accordingly provided an electric heater hav-ing a heating element which is arranged to lie in one plane and by arranging the heating element in' this manner it may be spaced at a given distance from the external object, the distance being uniform at all points throughout the heated area. The heating element, however, being disposed in one plane radiates heat theremoved from its containing casing or recep- This Idevice reflects the heat radiated from device disposed in a planesubstantially parallel with the plane of the heating element and spaced therefrom at la given distance.

theunused side of the heating element and .cumulatively adds it tothe heat radiated from the side of the heat-ing element on w-hich the external object is disposed. In this manner substantially all of the heat generated by the heating element is confined over an area where it is completely effective tov heat the external object.

The electric heater which I have shown in the drawings and in which my invention is embodied, isespecially adapted for toasting bread or for broiling meats. l have found by experiment that the most elfective heating capacity and the highest efficiency are obtained by disposing the food product to be heated, the heating element and the reflector in parallel planes and by spacing the food products at about one-half the distance from the lheating elementk as the heat reecto-r is -spaced therefrom. These proportions may vary within the range of one to one and one to two without material detriment to 'the eliiciency of the device. Tn this structure the heating element preferably comprises an electrical conductor 1 of suitable resistance to produce thedesiredtemperature with a given quantity of current and of suitable characteristics, to withstand the temperature to which it is subjected Without fusing or without deteriorating. The conductor is preferably a round wire forthe reason that it is the least expensive, but it will be understood, however, that a wire or rod of any desired cross section may be used. This conductor is preferably wound in a reflex or zigzag manner and is disposed in one plane.

It is retained in position by a base memberl of refractory insulating material 2 through the medium of L-shaped spring members 3 disposed in parallel rows on each side of the flanges 4 carried on the edges of said base member. One of these Lfshaped springs is preferably provided for each bend or bight in the conductor l. They are anchored atthe lower edges 5 of the outer face of the flanges 4 and extend vertically for a distance adjacent the outer faces of the flanges and then horizontally through suitable slots 6 provided in the upper edges of said flan es. At the inner ends of these springs are ooks 7 into which the conductor l is looped. These springs automatically com pensate for the expansion and contraction of the conductor l due to changes in tem-` perature thereof and thereby maintain the several portions of wire taut at all times so that they will not become displaced out of a horizontal plane. By arranging the springs in this manner they are protected by the flanges 4 'so that they lie almost wholly outside of the influence of the heat and in consequence their temper will not be impaired. The conductor l, in the structure shown, is wound to form a rectangle but, of course, it may be wound or otherwise arranged in a single plane of any geometric ligure. Furthermore the tension members or openings may be disposed in any suitable relation to the conductor to maintain it in its given plane. Of course if a conductor of\,suli cient rigidity to be self-maintaining were used,the tension members may be dispensed with.

The insulating base 2 is supported in the proper horizontal position within a suitable containing case or receptacle 10 by means of two plates ll secured to the bottom of the receptacle l() and extendingvvertically up-v ward. The upper edges of these plates lie adjacent the shoulders l2 on the underside of the base member and are intended to prevent said base member from shifting laterally.

The base member is clamped securely in position on the upper edges of these plates by the bolts 13, which also clamp the food grid in position,as will be hereinafter described. The space below the insulating base is pref- `erably filled with magnesia or some other loose, refractory heat insulating material (as shown in Figs. 2 and 5) to prevent the heat from reaching the casing and rendering it too hot for comfortable handling. It will be noted that the heating conductor and the insulating-support thereof comprise a unit heating element structure which is independent from the casing and the rest of the apparatus and which is easily removable therefrom. This is a desirable feature, since the heating element can be manufactured comparatively cheap, and inthe event that it should become burned out or otherwise damaged it Acan be conveniently7 removed from the receptacle and a new unit substi tuted at a slight cost. This unit heating element is insulated from the rest of the apparatus andgthe base .thereof is in metallic contact with the casing receptacle only at its points of'support at the upper edges of the supporting plates l1. Tt is thus separate from the casing by an air space, consequently an almost negligible quantity of the heat generated by the heating element will be dissipated in the casing.

Disposed upon the upper face of the insulating base 2, and lying substantially parallel with the plane of the heating elez ment, is the heat reflector 15. This preferably comprises a flat, rectangular, metallic .plate loosely slidable in side grooves formed by overhanging portions 16 of the flanges 4 on the insulating base. One end of th1s req fleotor projects through a slot 17 in the end' ofthe casing and has an upturned flange which substantially. closes said opening and which carries a small knob or handle 18 by which the reflector may be conveniently re- .movedor placed in position. The heat relector serves the additional purpose of n a removable crumb tray orl dripping tray.

The lcasing or receptacle 10 is open at its top. v Spanning this opening and dlsposed at a given relative distance above the heating elementiand in a'parallel plane thereto is the food' holder .or food grid. This grid is a supporting surface upon which bread, meat. or other o od'products may be laid. One end of this flange is continued downward to a point very close tothe bottom of the receptacle and serves not vonly to assist in spacing the insulating base from the end thereof, but it also serves to prevent food crumbs or 'grease drippings from falling into the lower part of the receptacle. As before menv tioned, the food grid is clamped in position by the bolts 13 which pass through the lugs 24. The structure which I have just described is particularly designed as a breadl toaster and will convenientlyaccomn'iodatev two slices of bread. Theheating element is in a sense divided into two divisions andl Veach division is substantially covered by a slice of bread. One of the reflex portions.y of the conductor is omitted to provide a gap between these two divisions, this being left.V

in order that the temperature will not become too great at the center of the devicel and scorch the adjacentedges of the two slices of bread. The upper faces 25 of the flanges are arranged to diverge or flare outwardly so as to increase the heat area of the device. It is desirable, though not necessary, in the use of this device that the object or article to be heated cover substantially the entire heated area since it is evident that all of the heat generated by the heating element will then beutilized. The casing or receptacle 10 is preferably formed up from sheet metal and 1s made to present a neat appearance. 1t is provided withy suitable legs 10' .and with handles 262 onthe ends by which it can be conveniently carried from vplace to piace.

sferring now to 31 have shown a tray or pan 27 having a handle 28 on each end and having a llat bottom which covers the entire upper area of the receptacle. This pan may be used in two positions, (as will be 4seen by the full and dotted lines in said figure) either as a fry pan, when it is in its normal position with its sides upturned, or a`s .a griddle plate when lin an inverted position.

Depending from the under face of the insulating base 2, near one end thereof, is a block of linsulating material 30 to which are secured two plates 31 serving as terminals for the heating element, the ends of the conductor 1 being connected by suitable leads 32 lying 011 the under face ofl the insulating base and extending to the terminal plates 31. These terminal plates 31 extend throiigh the opening in the bottom of the casing 10 and lie within a plug socket or receptacle 33 which is secured to the bottom of the casing 10 and which has lateral guide flanges 34 to maintain the connecting plug in connection with the terminal plates 31. The connecting plug is composed of two parts 35 of insulating material clamped together by bolts 36 and having registering depressions 37 in their adjacent faces in which depressions the contact terminals'38 are arranged, their bin'ding posts 39 being inclosed between the twoparts of the plug. The forward end of this plug is provided with two slots 40 which permit the terminal plates 31 to enter and make contact with the contact terminals 38 of the plug, and the rear end of the plug is provided with a: single opening 41 tl rough which the electric conductors 42, representing the source of electric current, enter the plug. Surrounding these conductors 42 is a spiral spring 43, anchored at one of its ends 44 to the plug and freely extensible along the conductors -in a direction away from the plug. Thisvspring hassecured to it about midway of its length a suitable knob 45. The purpose of this arrangement is to permit the plug to be removed from its socket and the circuit to be quickly broken. in order to revent undue burning .of the contacts. T e plug, as will be noticed, is inserted almost wholly within its socket and isheld therein by'friction. When it is desired todisconnect the heater' from the source of current the spring 43 is extended by pulling upon the knob 45. This places a tension upon the plug and as soon as this tension overcomes the friction between the my invention. For example, it is obviousV that windings of the conductor may be permanently secured at one side of the insulating base and held in tension by a single movable element or comb at the other side of the base. lt will also be understood that the heating elements may be arranged either singly or in pairs and supported in inclined or vertical positions and the means for supporting and protecting the heating element may be modified according to the uses to which the device is to be put. Still other modifications may be made and employed within the scope of `my invention, and 'for the reasons here stated l desire it to be understood that my invention is not limited or confined to the specific structure herein shown and described.

I claim:

1. In an electrical heater a heating element comprising a non-insulated electrical conductor openly wound to lie in one plane,-

an insulating support therefor adapted to maintain said heating element in lsaid plane, a flat heat reflector plate removably placed upon said insulating support in parallel relation to and at a fixed predetermined distance from said heating element, a food holding grid for maintaining an article to be heated in parallel relation' to the opposite side of said heating element and at a given distance therefrom, and a container case removably holding said parts in their relative position, and having an opening in one end for permitting the removal of the'y reflector plate. y

2. In an electrical heater a heating ele-- ment comprising a non-insulated electrical conductor reHeXively wound to lie in one plane, an insulating base plate, up-standing flanges on the side edges of said base, compensating springs upstanding from said base and passing through said flanges for maintaining said heating element in said plane, a heat reflector carried by said insulating support in parallel relation to and at a given distance from said heating element, and an openwork grid for m'aintaining'an article to be heated in parallel relation to the opposite side of'said vheating element and at a given distance therefrom, said parts coperating to confine ythe effective heat substantially on the side of said element adjacent the article to be heated.

In an electrical heating device a suitable casing, an insulating base supported therein and having upstanding flanges, and a non-insulated heating conductor wound to lie in a single plane, said base and conductor constituting a removable heater unit, and temperature compensating spring eX- tending through said flanges for supporting said conductor in its given plane regardless of the contraction and expansion of said velectrical conductor due to variations in at a glvendistaiice from said heating conductor.

In an electrical heating device a suitable casing, an insulating. base supported therein, a heating element comprising an electrical conductor arranged in a single plane, individual protected compensating devices carried. upon said insulating support and connected to different partsof sa-idheating element for maintaining said heating element in its given plane regardless of the contraction and expansion ofsaid electrical conductor due to variations in temperature thereof, heatL insulating barriers interposed between said individual compensating devices 'and saidy conductor, a heat reflector plate supported by said insulating base in parallel relation to and at a given distance from one side of said heating element, and a food grid supported byvsaid casing parallel to and at a given distance from the side opposite to the heat reflector. p

6. An electrical heater comprising a casing or receptacle vopen at its top, an insulating base member supported within saidv casing adjacent the open top thereof, a relatively thin heating element comprising an electricalconduotor wound in one plane, a plurality of protected spring tensioning devices carried upon said insulating base and connected to ldifferent points of said heating element for taking up the slack due to the expansion of said electrical conductor, and slotted heat insulating barriers on'said base through which said tensioning devices pass, said base and heating element constituting a heater unit dechable from said receptacle, a heat reflector plate removably mounted on said insulating base in arallel relation to and at agiven distance bellow said heating clement, and a food grid spanning the open top vof said receptacle and lying parallel to and at a given distance above said heating element.

7. ln an electrical toaster the combination with a suitably formed receptacle, an insulating base member supported within llo said receptacle, va non-conined heating element comprising an electrical conductor refiexively laid in one plane, a plurality of yielding L-shaped spring members extending through-said' base member and individually connected to said electrical conductor at the bends therein for maintaining said heating element in its given plane irrespective of the contraction and expansion of said electrical conductor, said insulating base and said heating element being removable as a unit from said receptacle, afood grid supported by said receptacle parallel `to and at a given distance above said heating element, and a heat reflector supported on said insulating base at not more than twice said given distance below said heating element.

8. In an electrical heating device the com,- bination with a suitable receptacle, an insulating base having side barriers, and a heating conductor carried thereby together comprising a removable heater unit, and a plurality of spring members disposed behind said barriers and connected, to different points of said heating. element for constantly maintaining it in a single plane irrespective of the contraction and expansion thereof, said spring members being protected by said barriers from the influence of said heating element.

9. In an electrical heater the combination with a suitable receptacle open .at its top, an insulating base member and a thin, openly Wound, electrical heating element carried thereby, plates upstanding fromthe bottom of said receptacle supportingsaid base upon their edges within said receptacle but out oi' contact with the walls thereof and adjacent to said open top, said parts being removable from said receptacle as a,

unit, a heat reflector plate carried upon said,1 base member below said' heatingl element, and .a separable food grid spanning 'the opening in said receptacle and arranged above said heating element, all of said parts cooperating to render cumulatively effective on the food grid side of said heating element substantially all of the heat radiated from both sides of said-heating element.

10. In an electricall heater the combination with a suitable receptacle, of an insulating base member contained within said receptacle, upwardly directed flanges on opposite sides of said base member, transverse slots in said flanges, a plurality of L-shaped spring hooks supported on the outer faces of said flanges andhaving a portion extending through said slots, and an electrical heating conductor reieXively Wound in a single plane and being supported at the bend ineach reflex by said spring hooks, said spring hooks serving to maintain said electrical conductor in its given plane irrespective of the contraction and expansion thereof.

11. In an electrical heating 'device the vcombination with a receptacle, of a unitary heating element removably mounted within said receptacle, said heating element comprising an insulating base and an electrical conductor doubled back upon itself a plurality of times and disposed in a single plane, and upstanding yieldingspring device's on said base member for individually supporting said conductor at the. bends therein, and barriers on said base for protecting said springs Jfrom the heating influence of said conductor.A

12. In an electrical heating device the combination with a receptacle, of a unitary heating 4element removably Vmounted within said receptacle, said heatingelement com- .prising an insulating base andan electrical tion with a suitable casing having an opening in its bottom and a-unitary heating element l comprising a refractory insulating base member and a non-confined, openly wound electrical conductor supportedthereby in one plane, 'said heating element being removable from said casing, a block of insulating material mounted upon and depending from said base member, terminals carried by said block and projecting through the opening in said casing, a plug socket depending from said casing adjacent the opening therein and a connection plug removably retained in said socket in contact with said terminals.

14. In an electric heater the combination with a casing, and a heating unit disposed within said casing and comprising an insulating base and a non-insulated, openly Wound, electrical heating conductor supported thereby and arranged in one plane en tirely out of contact with said base, said heating unit being separated from said casing by an air space, and loose refractory heat insulating substance substantially Elling said space.

15. An electrical heating device comprising a casing having an opening therein, an

insulating base and a heating element carried thereby contained within said casing, terminals for said heating element a column of insulating material carried by said insulating base, supporting said terminals and projecting through the openinginsaid casing, a plug socket carried by said easing adjacent the opening therein, a detachable con' nection plug retained in said socket in env casing so as to leave an air space surround.

ing said heater unit, and loose heat insulating material substantially filling said space.

17. 1n an electric toaster a suitably formed casing open at its top, a'removable heater unit consisting of a plate of refractory insulating material, a non-insulated conductor openly wound in a single plane parallel to and above said plate, and means on said plate connected to said conductor at diderent points for keeping it in its given plane, a thin strip upstanding edgewise from the bottom of said-casing and supporting said heater unit close to the open top of the casing and out of contact wit-h the casing so as to leave an air space around said heater unit, and loose heat insulating material, such as asbestos and magnesia, substantiallyv lling the space below said heater unit.

18. ln an electric toaster a suitably formed casing open at its top, a removable heater unit consisting of a plate of refractory insulating material, a non-insulated conductor openly wound in a single plane parallel to and above said plate, and means on said plate connected to. said conductor at dierent points for keeping it in it`s given plane, a thin strip upstanding edgewise from the bottom of said casing and supporting said heater unit close to the open top of the casing and out of contact with the casing so as to leave an air space around said heater unit, loose heat-insulatin material, substantially filling the space elow said heater unit,said casing having an opening in its bottom, and insulated Contact memes blades depending from said insulating plate through said opening.

19. An electric'heater comprising a plate of refractory insulating material, flanges upstanding from the edges of said plate, a conductor wound in a single plane between said flanges, and individual spring tension members upstanding from said plate adjacent the outer faces of said flanges and connected to different points of said conductor for autbmatically maintaining the individual turns of said conductor in a common plane.

20. An electric heater comprising a flat plate of refractory insulating material having upstanding side flanges, a heating conductor wound parallel to and vabove lsaid plate and in a single plane, openings in said flanges, and a'plurality of spring members anchored along the outside of said flanges and passing through said openings into individual connection with the several turns .of said conductor for automatically keeping said conductor vin its given plane.

2l. An electric heater comprising a plate of refractory insulating material, flanges upstanding from the edges of said plate, a conductor wound in a single plane between said flanges, a plurality of spring tension members upstanding from said plate adjacent the outer faces of said flanges and independently connected to dierent points of said conductor for automatically maintaining said conductor in its given plane, and a separable reflector plate laid upon said plate between said anges.

22. Ain electric heater comprising a plate of refractory insulating material, anges upstanding from the edges of said plate, a conductor wound in a single plane and disposed between said Hanges, tension members upstanding from said plate adjacent the outer faces of saidflanges and connected to different points of said conductor for automatically maintaining said conductor in its given plane, a block of insulating material depending from said insulating plate, and`terminals for said conductor supported by said block. v A

lln testimony whereof, 1 have hereunto set my hand, this 29th day of June, 19910, in the presence of two subscribing witnesses,

CHARLES 1P. ll/ADSEN,

Witnesses:

M. SIMON, JOHN R. LEFEVRE. 

